I use Madsonic mostly for streaming audiobooks to my phone and while its a great app for music (and good for audiobooks) there are a couple of features that would make it just as great for audiobooks.

One feature I would love to have is the sleep timer that can be found in many apps made specifically for audiobooks.Basically you set the timer to however long you want and then after that time the player pauses.Another feature I would like is for the client to remember the location or at least track I was at when I closed it.